Anthropogenic effects on urban and coastal climates

1
Anthropogenic effects on urban and coastal
climates

• R. Bornstein
• and co-workers
• San Jose State University
• pblmodel_at_hotmail.com
• Presented at
• Stanford University
• 9 April 2007

2
OUTLINE

• Global warming observations in Calif
• Reverse impacts
• Daytime summertime coastal-cooling
• Urbanized meso-met modeling
• uMM5
• Houston
• NYC
• uWRF plans

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(Part 1) Global-warming reverse-impactobserved
summer-daytime coastal-coolingin California
air-basins

• R. Bornstein, San Jose State University
• pblmodel_at_hotmail.com
• B. Lebassi, J. E. González, D. Fabris,
• E. Maurer, Santa Clara University
• N. Miller, Berkeley National Laboratory

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OUTLINE

• Global-warming ? reverse impacts
• Coastal-cooling observations
• Methodology
• Results
• South Coast Air Basin
• SFBA and Central Valley
• Conclusion
• Summary
• Implications
• FUNDING Santa Clara University

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Global Warming

• Models past future asymmetric-warming
• (i.e., ?Tmin gt ?Tmax) on
• global scale (1.0-2.5 deg resolution)
• regional scale (10 km resolution)
• Global scale obs
• match model results
• show accelerated-
• warming since 70s ?

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California Warming JJA 1900-2000 ?-Taver(K)

• USC Stat-downscaled global-model results
• 2-m AGL
• 10-km horiz-grid
• warming-rates decrease towards coast
• Coastal SSTs
• ICOADS data
• 2-deg horiz resolution
• Warming, but
• At slower rate than at inland sites

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Reverse-Impact Hypothesis

• INLAND WARMING ?
• INCREASED (COAST TO INLAND) ?(p,T)/?n?
• INCREASED SEA BREEZE FREQ, INTENSITY,
  PENETRATION, DURATION ?
• COOLING SUMMER COASTAL Tmax

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CALIF TEMP-DATA

• FROM NCDC
• 2-m VALUES
• DAILY TMAX TMIN
• 300 NWS CO-OP SITES
• 1948-2005

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ANALYSES

• 1970-2005 data
• Annual summer warming/ cooling trends
  (K/decade) for SST, Tmax, Tmin
• Spatial dist of summer
• Tmax-trends plotted
• (in 2 black boxes)
• South Coast Air Basin
• SFBA and Central Valley
• Summer land-sea Taver-grad (surrogate for p-grad)
  trend calculated by use of
• SST SFBA black-box ocean
• 2-m land-values red-box

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Calif Asymmetric-Warming 1970-2005

• Middle curve (Tmin)
• 0.27 K/decade
• Lower curve (Tmax)
• 0.061 K/decade
• (small-? b/t 2 large nos.)
• Top curve (SST)
• 0.24 K/decade
• Thus, from Taver SST
• Right curve (T-grad)
• 0.16 K/100-km/decade ?
• stronger sea breeze

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• Changes in Diurnal temperature-range (DTR)
  values all of Calif
• daytime-warming (mainly inland) sites 0.05
  K/decade
• (as Tmax increased a bit faster than did Tmin
  why?)
• daytime-cooling (mainly coastal) sites -0.61
  K/decade
• (as Tmax decreased Tmin increased)

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Significant South Coast Air Basin Topography
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SCAB 1970-2005 summer Tmax warming/cooling
trends (K/decade)
Arrows dominant summer flow
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Significant SFBA and CenValley Topography
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SFBA CenV 1970-2005 summerTmax warming/cooling
trends (K/decade)
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Statistical Significance 1970-2005
Parameter (all Calif) Rate (K/decade) r Ne (years) Significance ()
DTR (cooling areas) -0.61 0.70 6 95
DTR (warming areas) 0.05 0.07 31 32
Tmin 0.27 0.52 11 93
Tmax 0.06 0.09 30 68
SST 0.24 0.45 14 92
100-km dT/dx 0.16 0.10 30 40
Region-Area Rate (K/decade) r Ne (years) Significance ()
Coastal-SFBA -0.16 0.23 22 72
Inland-SFBA 0.47 0.58 10 95
Coastal-SoCAB -0.33 0.37 17 87
Inland-SoCAB 0.21 0.25 22 74
Coastal-Both -0.22 0.32 19 83
Inland-Both 0.40 0.53 11 93
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SUMMARY

• MIN-TEMPS IN CALIF WARMED FASTER THAN MAX-TEMPS ?
  ASYMMETRIC WARMING
• SUMMER DAYTIME MAX-TEMPS COOLED IN LOW-ELEVATION
  COASTAL AIR- BASINS
• FOLLOWING AREAS COOLED IN CENTRAL CALIFORNIA
• MARINE LOWLANDS
• MONTEREY
• SANTA CLARA VALLEY
• LIVERMORE VALLEY
• WESTERN-HALF OF SACRAMENTO VALLEY

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GOOD IMPLICATIONS

• AGRICULTURAL AREAS MAY NOT SHRINK
• e.g. NAPA WINE AREAS MAY NOT GO EXTINCT
  ?
• ENERGY-NEED FOR COOLING MAY NOT INCREASE AS
  RAPIDLY AS POPULATION
• LOWER HUMAN HEAT-STRESS MORTALITY RATES
• URBAN-OZONE LEVELS WILL CONTINUE TO FALL

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IMPLICATIONS FOR CALIF OZONE

• PAST DECREASES MAY BE IN-PART DUE TO JJA MAX-TEMP
  COOLING-TREND NOT ONLY TO EMISSION REDUCTIONS
• WHEN MAX-T DECREASES, THE FOLLOWING ALSO
  DECREASE
• BIOGENIC PRECURSOR EMISSIONS
• PHOTOCHEM REACTION RATES
• ENERGY-USE FOR COOLING AND THUS ANTHROPOGENIC
  PRECURSOR EMISSIONS

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REQUIRED FUTURE-EFFORTS

• ANALYSIS OF OBS MESO MET MODELING
• TO SEPARATE-OUT INFLUENCES
• (DISCUSSED IN LITERATURE) OF
• WARMING SSTs ?
• weaker sea breezes
• INCREASED COASTAL UPWELLING ?
• stronger sea breezes
• LAND-USE CHANGES
• AGRICULTURAL INCREASED INLAND IRRIGATION ?
• inland cooling ? decreased sea-breezes
• URBANIZATION STRONGER UHIs ?
• increased sea-breezes
• OTHER SEA-BREEZE INFLUENCES
• INCREASED WIND VELOCITY, STRATUS CLOUD COVER,
  SOIL MOISTURE ?
• coastal cooling

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WHERE TO LOOK FOR COASTAL-COOLING

• GC winds in same-direction as sea-breeze
• Low-elevation air-basins
• Cool coastal ocean-currents
• Upwelling areas
• i.e. mid-lat (what lat range?) west-coast areas
• What other-types of reverse-impacts might exist,
  e.g., in mt areas?

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Part 2 Urbanized Mesoscale Atmospheric Modeling

• R. Bornstein, R. Balmori, H. Taha
• San Jose State University
• San Jose, CA
• pblmodel_at_hotmail.com
• Presented at
• NRL Monterey, CA
• 6 October 2006

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OUTLINE

• uMM5
• Houston ozone
• NYC tracer study
• (Future) uWRF
• Conclusion
• Funded by TCEQ, NSF, DHS

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Urbanization History

• Urbanize momentum, thermoynamic, TKE
• surface SBL diagnostic eqs
• PBL prognostic eqs
• From veg-canopy model (Yamada 1982)
• Veg-param replaced with GIS/RS urban-param/data
• Brown and Williams (1998)
• Masson (2000)
• Martilli et al. (2001) in TVM/URBMET
• Dupont, Ching, et al. (2003) in EPA/MM5
• Taha et al. (2005), Balmori et al. (2006b) in
  uMM5
• Detailed input urban-parameters as f(x,y)
• Next 2 slides

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Within Gayno-Seaman PBL/TKE scheme
From EPA/MM5 Mason Martilli (by Dupont)
26
_________
______
3 new terms in each prog equation
? Advanced urbanization scheme from Masson (2000)
27
New GIS/RS inputs for uMM5 as f (x, y, z)

• land use (38 categories)
• roughness elements
• anthropogenic heat as f (t)
• vegetation and building heights
• paved-surface fractions
• drag-force coefficients for buildings
  vegetation
• building height-to-width, wall-plan,
  impervious-
• area ratios
• building frontal, plan, and rooftop area
  densities
• wall and roof e, c?, a, etc.
• vegetation canopies, root zones, stomatal
  resistances

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MM5 input-table urban z0

• z0 80 cm
• Too low for tall-cities obs up to 3-4 m
• Urban-winds are thus too fast
• Must adjust input via GIS/RS f(x,y)
• See next slide

29
S. Stetson Houston GIS/RS zo input
Values are too large, as they were f(h) and not
f(oh)
Values up 3 m
30
Martilli/EPFL q2-results
Urbanization ? day nite on same line ?
stability effects not important
Non-urban
urban
Urban model values gt rooftop max gt match obs
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uMM5 for Houston Balmori (2006)

• Goal Accurate urban/rural temps winds for
• Aug 2000 O3 episode by use of
• gt uMM5
• gt Taha-modified Houston LU/LC urban
  morphology parameters
• Additional processing of Burian parameters
• Modification of uMM5 to accept these data
• gt TexAQS2000 field-study met 03 data
• gt USFS urban-reforestation scenarios ?
• lower daytime UHI-intensities O3

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D-5 UTC episode-day obs of meso O3
transport-patterns influences of sea breeze
UHI-convergence

• GC influences small
• Air-mass movement first
• along-shore (to east) due to flow along
• N-edge of cold-core atm-low
• Then from Ship Channel to Houston by
• Bay Breeze then to Houston by UHI-con ?
• max O3
• Finally NW of Houston by Gulf Breeze
• Contours 5 ppb (00-16 UTC) then 10 ppb

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(No Transcript)
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uMM5 Simulation period 22-26 August 2000

• Model configuration
• 5 domains 108, 36, 12, 4, 1 km
• (x, y) grid points
• (43x53, 55x55, 100x100, 136x151, 133x141
• full-s levels 29 in D 1-4 49 in D-5 lowest ½
  s-level7 m
• 2-way feedback in D 1-4
• Parameterizations/physics options
• Grell cumulus (D 1-2) ETA or MRF PBL (D 1-4)
• Gayno-Seaman PBL (D-5) Simple ice moisture,
• urbanization module NOAH LSM RRTM radiative
  cooling
• Inputs
• NNRP Reanalysis fields, ADP obs data
• Burian urban morphology from LIDAR
  building-data in D-5
• LU/LC modifications (from Byun)

35
Episode-day synoptics 8/25, 12 UTC (08 DST)
Surface
700 hPa
700 hPa sfc GC Hs at their weakest (no
gradient) over Texas ? meso-scale forcing (sea
breeze UHI-convergence) will dominate
36
Concurrent NNRP fields at 700 hPa sfc
D p2 hPa
NNRP-input to MM5 (as IC/BC) captured GC/synoptic
features, as location strength of high were
similar to NWS charts (previous slide)
37
MM5 episode day, 3 PM gt D1 reproduces weak
GC p-grad flowgt D-2 coastal (cold-core) L
emerges (in weak form) gt D-3 well formed L ?
along-shore V
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Domain 4 (3 PM) Note cold-core L off of Houston
on O3 day (25th)
? Episode day
L
L
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Urbanized Domain 5 near-sfc 3 PM V on 4
successive days
H
C

• Episode
• day

40
Along-shore flow, 8/25 (episode day) obs at 1500
UTC vs uMM5 (D-5) at 2000 UTC
D-5 (red box) uMM5 captured HGA obs of
along-shore flow (from SST- BC cold-low)
C
41
1 km uMM5 Houston UHI 8 PM, 21 Aug

• Upper, L MM5 UHI (2.0 K)
• Upper, R uMM5 UHI (3.5 K)
• Lower L (uMM5-MM5) UHI

LU/LC error
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8/23 Daytime 2-m UHI obs vs uMM5 (D-5)
H
43
Along shore flow came from Cold-Core L D-3 MM5
vs Obs Temps
H
Obs (18 UTC) gt Cold-core L (only 1-ob) gt
Urban area (blue-dot clump) retards cold-air
penetration

• MM5 produces coastal cold-core low

44
UHI-Induced Convergence obs vs. uMM5
OBSERVED
uMM5
45
Obs speeds (m/s) in area of D-5 sfc roughness ?
speed-decrease over two Houston urban-cores

-

-

-

V
46
Base-case (current) vegetation cover in 0.1s
(urban min)
Modeled increases in vegetation cover (urban
max) values in 0.01s
47
Soil moisture increase for Run 12 (entire area,
left) Run 13 (urban area only, right)
48
Run 12 (urban-max reforestation) minus Run 10
(base case) near-sfc ?T at 4 PMreforested
central urban-area cools surrounding deforested
rural-areas warm
49
DUHI(t) for Base-case minus Runs 15-18

• UHI Temp in urban-box minus Temp in rural-box
• Runs 15-18 different urban re-forestation
  scenarios
• DUHIRun-17 UHI Run-13 UHI (max effect, green
  line)
• Reduced UHI ? lower max-O3 (not shown) ?
• EPA emission-reduction credits ? saved

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FUTURE WORK uWRF

• Urbanize WRF with F. Chen at NCAR for DTRA
• Martilli-Dupont-Taha urbanization
• Freedman turbulence
• Possible applications
• Urban-canyon dispersion for DTRA (awarded)
• NYC-ozone for EPA
• Calif-ozone for CARB
• Urban-thunderstorms for NSF
• Urban wx-forecasting for NWS

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THANKS!Any further questions?